Consider

Psychic Corrosion

Whenever you draw a card, each opponent mills two cards.

Have

Mystical Tutor

Search your library for an instant or sorcery card, reveal it, then shuffle and put that card on top.

Insight Engine

{2}, {T}: Put a charge counter on this artifact, then draw a card for each charge counter on it.

Tasha's Hideous Laughter

Each opponent exiles cards from the top of their library until that player has exiled cards with total mana value 20 or greater.

Island

Aetherize

Return all attacking creatures to their owner's hand.

Maddening Cacophony

Kicker {3}{U}
Each opponent mills eight cards. If this spell was kicked, instead each opponent mills half their library, rounded up.

Mesmeric Orb

Whenever a permanent becomes untapped, that permanent's controller mills a card.

Three Steps Ahead

Spree (Choose one or more additional costs.)
+ {1}{U} — Counter target spell.
+ {3} — Create a token that's a copy of target artifact or creature you control.
+ {2} — Draw two cards, then discard a card.

Rhystic Study

Whenever an opponent casts a spell, you may draw a card unless that player pays {1}.

Labyrinth of Skophos

{T}: Add {C}.
{4}, {T}: Remove target attacking or blocking creature from combat.

Strionic Resonator

{2}, {T}: Copy target triggered ability you control. You may choose new targets for the copy. (A triggered ability uses the words "when," "whenever," or "at.")

Personal Tutor

Search your library for a sorcery card, reveal it, then shuffle and put that card on top.

Turnabout

Choose artifact, creature, or land. Tap all untapped permanents of the chosen type target player controls, or untap all tapped permanents of that type that player controls.

Meekstone

Creatures with power 3 or greater don't untap during their controllers' untap steps.

Solve the Equation

Search your library for an instant or sorcery card, reveal it, put it into your hand, then shuffle.

Collective Restraint

Domain — Creatures can't attack you unless their controller pays {X} for each creature they control that's attacking you, where X is the number of basic land types among lands you control.

Kindred Discovery

As this enchantment enters, choose a creature type.
Whenever a creature you control of the chosen type enters or attacks, draw a card.

Compulsion

{1}{U}, Discard a card: Draw a card.
{1}{U}, Sacrifice this enchantment: Draw a card.

Crawlspace

No more than two creatures can attack you each combat.

Bruvac the Grandiloquent

If an opponent would mill one or more cards, they mill twice that many cards instead. (To mill a card, a player puts the top card of their library into their graveyard.)

Fabricate

Search your library for an artifact card, reveal it, put it into your hand, then shuffle.

Endless Atlas

{2}, {T}: Draw a card. Activate only if you control three or more lands with the same name.

Dissipation Field

Whenever a permanent deals damage to you, return it to its owner's hand.

Reconsider

Reflections of Littjara

As this enchantment enters, choose a creature type.
Whenever you cast a spell of the chosen type, copy that spell. (A copy of a permanent spell becomes a token.)

The One Ring

Indestructible
When The One Ring enters, if you cast it, you gain protection from everything until your next turn.
At the beginning of your upkeep, you lose 1 life for each burden counter on The One Ring.
{T}: Put a burden counter on The One Ring, then draw a card for each burden counter on The One Ring.

Thrumming Stone

Spells you cast have ripple 4. (Whenever you cast a spell, you may reveal the top four cards of your library. You may cast spells with the same name as that spell from among the revealed cards without paying their mana costs. Put the rest on the bottom of your library.)

Propaganda

Creatures can't attack you unless their controller pays {2} for each creature they control that's attacking you.

Command Beacon

{T}: Add {C}.
{T}, Sacrifice this land: Put your commander into your hand from the command zone.

Getting

Commander's Plate

Equipped creature gets +3/+3 and has protection from each color that's not in your commander's color identity.
Equip commander {3}
Equip {5}

Traumatize

Target player mills half their library, rounded down.

Mystifying Maze

{T}: Add {C}.
{4}, {T}: Exile target attacking creature an opponent controls. At the beginning of the next end step, return it to the battlefield tapped under its owner's control.

Reality Spasm

Choose one —
• Tap X target permanents.
• Untap X target permanents.

Glacial Chasm

Cumulative upkeep—Pay 2 life. (At the beginning of your upkeep, put an age counter on this permanent, then sacrifice it unless you pay its upkeep cost for each age counter on it.)
When this land enters, sacrifice a land.
Creatures you control can't attack.
Prevent all damage that would be dealt to you.

Ever-Watching Threshold

Whenever an opponent attacks, if they attacked you and/or a planeswalker you control, draw a card.

Academy Ruins

{T}: Add {C}.
{1}{U}, {T}: Put target artifact card from your graveyard on top of your library.

Overture

Target opponent mills half their library, rounded down. (Then exile this card. You may play the land later from exile.)

Jidoor, Aristocratic Capital

Jidoor, Aristocratic Capital // Overture

Mindcrank

Whenever an opponent loses life, that player mills that many cards. (Damage causes loss of life.)

Jace, Memory Adept

+1: Draw a card. Target player mills a card.
0: Target player mills ten cards.
−7: Any number of target players each draw twenty cards.

The Water Crystal

Blue spells you cast cost {1} less to cast.
If an opponent would mill one or more cards, they mill that many cards plus four instead.
{4}{U}{U}, {T}: Each opponent mills cards equal to the number of cards in your hand.

Maze of Ith

{T}: Untap target attacking creature. Prevent all combat damage that would be dealt to and dealt by that creature this turn.

Unstoppable Plan

At the beginning of your end step, untap all nonland permanents you control.

Fractured Sanity

Each opponent mills fourteen cards.
Cycling {1}{U} ({1}{U}, Discard this card: Draw a card.)
When you cycle this card, each opponent mills four cards.

Cosmos Elixir

At the beginning of your end step, draw a card if your life total is greater than your starting life total. Otherwise, you gain 2 life.

Locket of Yesterdays

Spells you cast cost {1} less to cast for each card with the same name as that spell in your graveyard.

Betrayal

Enchant creature an opponent controls
Whenever enchanted creature becomes tapped, you draw a card.

Mystic Remora

Cumulative upkeep {1} (At the beginning of your upkeep, put an age counter on this permanent, then sacrifice it unless you pay its upkeep cost for each age counter on it.)
Whenever an opponent casts a noncreature spell, you may draw a card unless that player pays {4}.

Customs Depot

Whenever you cast a creature spell, you may pay {1}. If you do, draw a card, then discard a card.

Persistent Petitioners

{1}, {T}: Target player mills a card. (They put the top card of their library into their graveyard.)
Tap four untapped Advisors you control: Target player mills twelve cards.
A deck can have any number of cards named Persistent Petitioners.